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//
// ========================================================================
// Copyright (c) 1995-2016 Mort Bay Consulting Pty. Ltd.
// ------------------------------------------------------------------------
// All rights reserved. This program and the accompanying materials
// are made available under the terms of the Eclipse Public License v1.0
// and Apache License v2.0 which accompanies this distribution.
//
// The Eclipse Public License is available at
// http://www.eclipse.org/legal/epl-v10.html
//
// The Apache License v2.0 is available at
// http://www.opensource.org/licenses/apache2.0.php
//
// You may elect to redistribute this code under either of these licenses.
// ========================================================================
//
package org.eclipse.jetty.servlets;
import java.io.IOException;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
/* ------------------------------------------------------------ */
/** User Agent Filter.
* <p>
* This filter allows efficient matching of user agent strings for
* downstream or extended filters to use for browser specific logic.
* </p>
* <p>
* The filter is configured with the following init parameters:
* <dl>
* <dt>attribute</dt><dd>If set, then the request attribute of this name is set with the matched user agent string</dd>
* <dt>cacheSize</dt><dd>The size of the user-agent cache, used to avoid reparsing of user agent strings. The entire cache is flushed
* when this size is reached</dd>
* <dt>userAgent</dt><dd>A regex {@link Pattern} to extract the essential elements of the user agent.
* The concatenation of matched pattern groups is used as the user agent name</dd>
* <dl>
* An example value for pattern is <code>(?:Mozilla[^\(]*\(compatible;\s*+([^;]*);.*)|(?:.*?([^\s]+/[^\s]+).*)</code>. These two
* pattern match the common compatibility user-agent strings and extract the real user agent, failing that, the first
* element of the agent string is returned.
*
*
*/
public class UserAgentFilter implements Filter
{
private static final String __defaultPattern = "(?:Mozilla[^\\(]*\\(compatible;\\s*+([^;]*);.*)|(?:.*?([^\\s]+/[^\\s]+).*)";
private Pattern _pattern = Pattern.compile(__defaultPattern);
private Map<String, String> _agentCache = new ConcurrentHashMap<String, String>();
private int _agentCacheSize=1024;
private String _attribute;
/* ------------------------------------------------------------ */
/* (non-Javadoc)
* @see javax.servlet.Filter#destroy()
*/
public void destroy()
{
}
/* ------------------------------------------------------------ */
/* (non-Javadoc)
* @see javax.servlet.Filter#doFilter(javax.servlet.ServletRequest, javax.servlet.ServletResponse, javax.servlet.FilterChain)
*/
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException
{
if (_attribute!=null && _pattern!=null)
{
String ua=getUserAgent(request);
request.setAttribute(_attribute,ua);
}
chain.doFilter(request,response);
}
/* ------------------------------------------------------------ */
/* (non-Javadoc)
* @see javax.servlet.Filter#init(javax.servlet.FilterConfig)
*/
public void init(FilterConfig filterConfig) throws ServletException
{
_attribute=filterConfig.getInitParameter("attribute");
String p=filterConfig.getInitParameter("userAgent");
if (p!=null)
_pattern=Pattern.compile(p);
String size=filterConfig.getInitParameter("cacheSize");
if (size!=null)
_agentCacheSize=Integer.parseInt(size);
}
/* ------------------------------------------------------------ */
public String getUserAgent(ServletRequest request)
{
String ua=((HttpServletRequest)request).getHeader("User-Agent");
return getUserAgent(ua);
}
/* ------------------------------------------------------------ */
/** Get UserAgent.
* The configured agent patterns are used to match against the passed user agent string.
* If any patterns match, the concatenation of pattern groups is returned as the user agent
* string. Match results are cached.
* @param ua A user agent string
* @return The matched pattern groups or the original user agent string
*/
public String getUserAgent(String ua)
{
if (ua == null)
return null;
String tag = _agentCache.get(ua);
if (tag == null)
{
if (_pattern != null)
{
Matcher matcher = _pattern.matcher(ua);
if (matcher.matches())
{
if (matcher.groupCount() > 0)
{
for (int g = 1; g <= matcher.groupCount(); g++)
{
String group = matcher.group(g);
if (group != null)
tag = tag == null ? group : tag + group;
}
}
else
{
tag = matcher.group();
}
}
}
if (tag == null)
tag = ua;
if (_agentCache.size() >= _agentCacheSize)
_agentCache.clear();
_agentCache.put(ua, tag);
}
return tag;
}
}
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